There is proposed a capacitive combined sensor in which detecting sections that can detect acceleration and angular velocities as a plurality of physical quantities are combined and formed on one substrate. For example, JP-A-10-239347 (Patent Literature 1) and JP-A-2002-005950 (Patent Literature 2) respectively disclose examples of the combined sensor. The combined sensor disclosed in Patent Literature 1 and Patent Literature 2 detects motions in a plane of a device layer in which a movable section is formed. A detection capacitor, the capacitance of which increases according to the motion of the movable section, and a detection capacitor, the capacitance of which decreases according to the motion of the movable section, are formed in the same plane. The two capacitances are differentially input to a capacitance-to-voltage conversion section (a C/V conversion section), whereby an output of a signal to be detected is obtained. Since an angular velocity sensor and an acceleration sensor are provided on the same substrate, there is an advantage that the combined sensor can be manufacture inexpensively and can be easily reduced in size.
JP-T-8-501156 (the term “JP-T” as used herein means a published Japanese translation of PCT patent Application) (Patent Literature 3) and JP-A-2001-235381 (Patent Literature 4) respectively disclose examples of pressure sensors. In the pressure sensors disclosed in Patent Literature 3 and Patent Literature 4, a pressure-sensitive capacitive element, the capacitance of which changes according to application of pressure, and a reference capacitive element having a reference capacitor, the capacitance of which is invariable with respect to pressure to be detected, are formed on one substrate. The pressure sensor outputs a signal corresponding to a ratio of the two capacitances to thereby detect pressure.